My proposed project will examine the influence of the descending monoaminergic systems on the movement related receptive fields of spinal interneurons. The overall hypothesis is that the monoamines inhibit divergent sensory input to various spinal interneurons. These interneurons, which are interposed in various reflex pathways, thus have relatively narrow receptive fields. When monoaminergic control to these interneurons is disrupted, such as in spinal cord injury, previously inhibited sources of movement related sensory input are released, exerting uncoordinated facilitation or inhibition of the interneuron. Briefly, I plan to test this hypothesis by performing extracellular recordings of various classes of interneurons utilizing a computer controlled robotic arm that can impose passive movements in three dimensions. I will examine the movement related receptive field size of interneurons before and after varying the monoaminergic input. I will also identify the specific monoaminergic receptor sub-types involved and determine if the neurotransmitter glutamate, which can have similar effects on neurons as the monoamines, works with the monoamines in regulating movement related receptive fields of spinal interneurons. [unreadable] [unreadable]